Just to be clear, the 12 segments are just an image of the partially assembled 16 segment mirror - the design hasn't changed
The long-awaited James Webb Space Telescope has finally been assembled, NASA announced on Wednesday. The project has had a rocky road. Originally scheduled to enter space as early as 2007, the instrument has been bedeviled with numerous delays, including a redesign and an accidentally ripped sunshield that had to be repaired. …
25 years ago there was a design with a single 6.5m monolithic mirror.
It needed an Ariane5 with a special 'power bulge' nose cone.
But it was imperative that the launch be on an American rocket, hence the complex folding design. Then the cost got so high they needed european partners.....
>Politics getting in the way?
Ah the stories I could tell of Hubble.
When it was first launched the mirror problem gave the public impression was that it was totally fscked.
In fact it was just 10x better than anything on the ground, but not 100x better
So there was a plan to take some impressive pretty pictures of pretty objects to show the public.
These were taken by a European camera and so had the ESA logo as well as the NASA logo. But the ESA logo is square, so at the same width looked larger than the NASA logo. So the publication was blocked until an agreement could be reached about the relative areas of the two logos.....
They were probably spherical mirrors (like an individual small telescope mirror) these are each different parabolic shapes as if you had made one vast parabolic mirror and sliced it up. It is WAY harder to build even with modern CNC machines
It was first done in the early 90s at Keck but took years and a few technology breakthroughs to eventually figure the mirror correctly. And learning how to align it perfectly took more years.
So doing this in space and having it faultlessly unfold and align perfectly a million miles away is going to be sphincter clenching (assuming they ever finish building it)
They were only using it as a zenith telescope to determine position of stars, so image quality wasn't a priority. Apparently they were spherically ground mirrors, though that is difficult to see with eyeballs!
His assistant (who was the guy adjusting all the screws) subsequently went to the US and is popularly credited with inventing segmented mirrors. Although he did improve them enormously I think the original guy should get some credit.
Why do the Septics claim to have invented everything? They are nearly as bad as the Sweaty Socks.
Originally scheduled to enter space as early as 2007, the instrument has been bedeviled with numerous delays ...
Delays and cost overruns are par for the course whenever you do something at the utmost limit of the technically possible, and especially so if you do this for the first time ever.
I have a very nice book by Robert W. Smith on my book shelf, with the title "The Space Telescope: A study of NASA, science, technology, and politics". It was published in 1989 - a year before Hubble was launched, and four year before it first worked as intended.
The author was contracted by NASA and NSF to document the construction and the initial operation of the space telescope; however by 1986 - after hundreds of those involved were interviewed, the scientific, technical, and legislative processes were extensively documented, the manuscript was completed, and the contracts have run out - the launch was still nowhere in sight and it remained uncertain whether it would ever happen at all.
Luckily, it did happen, and the rest is history - including the book, which I highly recommend to anyone interested in space science and science politics.
It will be great if it does get up to L2 and deploys all the various bits so it works. The whole thing is just so complicated basic odds suggest that something will not quite function as expected.
I believe the mirror is also dynamic as well and each panel needs to be manipulated to maintain the overall precision the instruments need.
There is just so much to go wrong and so very little that can done once it is at L2.
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